Lesson: Lung Module

Next, we will auto shape another beam around the CTV, and oppose the 1st beam (180 degrees apart). Our gantry angle for the 2nd beam is 206 degrees. This beam is also off-cord. Notice that again, the dose is greater on the anatomical left side of the treatment field. This is because there is a greater amount of air on that side. Therefore, there is less beam attenuation.

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